A real spin for precious data

A state-of-the-art centrifuge provides oil companies with even better data for decision making.

In special core analysis (SCAL) centrifuges are used for wettability studies and determination of capillary pressure and relative permeability of core samples from reservoirs.

Data for reservoir description
The new centrifuge at the IRIS petroleum laboratory is made by Vinci Technologies (France), and has automatic reading of produced volumes, exact control on rotational speed and temperature, and accommodate six core holders simultaneously. In addition, the software for interpreting data comes from Cydarex.

Centrifuge operation: The forces on the fluids inside a core in the centrifuge are similar to gravitational forces. For instance, starting with a water saturated core sample, these forces will drive out the water, while oil enters the sample. By increasing the rotational speed, the forces will increase, driving still more water out of the core.

From measuring the amount of water coming out of the sample at each speed, the capillary pressure versus saturation can be calculated.

Also the reverse process, with water entering the sample and oil being produced from the sample can be measured. Similarly, relative permeability can be determined from the rates at which the fluids are “produced” from the samples.

- The information derived from the centrifuge experiments, the capillary pressure, the relative permeability, the residual oil saturation and the wettability, are used by the oil companies in reservoir description. Consequently, it is part of the basis for assessing the best way oil can be extracted from the reservoirs, says Jan Erik Iversen, Research Engineer at IRIS's Petroleum Laboratories.

Important preparation
Iversen emphasise that for any SCAL experiment to be valid, proper core sample preparation is essential. That is; the samples must be properly restored to the reservoir conditions by cleaning, re-establishing connate water saturation, and ageing the samples with crude oil to establish reservoir wettability.

After comprehensive testing and adjusting, the centrifuge will be up and running by the end of the month.